This announcement just arrived via press release from the Cubs:
The Chicago Cubs game scheduled for Sunday, June 29, against the Washington Nationals at Wrigley Field has been moved to Saturday, June 28, as part of a separate admission, day-night doubleheader. This change was made at the request of Ald. Tom Tunney and in consideration of neighborhood traffic and congestion in connection with the annual Pride Parade in Chicago on June 29. The first game of the doubleheader will be played at 12:05 p.m. The second game is scheduled to start at 6:15 p.m. There will be no game Sunday, June 29.
In the past, the Cubs have attempted to get Major League Baseball to schedule them on the road on the weekend of the Pride Parade, which goes down Halsted Street within about three blocks of Wrigley Field. Since MLB couldn't accomodate the Cubs with that this year -- not sure of the reasons -- this seems a reasonable way to compromise.
The 6:15 p.m. CT start likely means the night game will be carried on Fox-TV. The current night-game ordinance does not allow Saturday night games unless they are televised on a national network.
Finally, I can't remember the last time — if there even has been such a time — when the Cubs played a weekend series at home without having a Sunday game involved.